N Read 2.3, 2.5 n Problems 1.6, 2.6, 2.8 n Quiz #1, Lecture 12, 4 February u Open book & notes u Calculators are allowed u No Smart Phones ECEN4533 Data.

Read 2.3, 2.5 Problems 1.6, 2.6, 2.8 Quiz #1, Lecture 12, 4 February

Open book & notes Calculators are allowed No Smart Phones

ECEN4533 Data CommunicationsLecture #4 14 January 2013Dr. George Scheets


Read 3.1 Ignore Probability Equations until Review

Scan Design Problem #1 Problems 2.7, 3.1, 3.2 Quiz #1

Lecture 12, 4 February (Live) < 11 February (Async Distance Learning)

Extra Credit (up to 20 points) Find errors in text or solutions.



Read 3.2 Problems 3.9, 3.10 Quiz #1

Lecture 12, 4 February (Live) < 11 February (Async Distance Learning)

Design #1 due 1 February (Live) 8 February (Async DL) Late = -1 per working day

No Class next Monday



PSTN Call SequencingPSTN Call Sequencing User Dials Number Routing Protocol Determines path thru network Affected Core Switches notified

Time Slots reserved to support callTime Slot = 1 byte every 1/8000 th second for 64 Kbps

Switches continuously move bytes arriving on input time slot(s) to appropriate output line and time slot(s)

User “sees” dedicated nailed up bandwidth Source TCP opens logical connection with Sink

Packets transferred, logical connection closed Switch resources released when user hangs up

ISDN connection using PSTNISDN connection using PSTN

Long Distance & Local Carriers dedicate 64 Kbps to our use (Circuit Switching).

node c

PSTNetwork

Nailed up Circuit

PC

node a

PC

Carrier PSTN NetworkCarrier PSTN Network

1

3PSTN Switch

TrunksAccess LinePC

PC

Switches move bytes from input to output.Bytes get moved at line speeds.Trunk capacity is dedicated.

Moving Traffic with PacketsMoving Traffic with Packets Layer 7 Application Word Perfect

2,920B file to move Layer 6 Presentation Windows API Layer 5 Session TCP Layer 4 Transport TCP

Maximum TCP Segment Size assumed to be 1460B(Parameter in Windows Registry)

Chops file into 2 x 1460B packets, adds 20B TCP Header to each Layer 3 Network IP

Adds 20B IP Header to each packet Layer 2 Data Link Undefined

Adds 10B Layer 2 Header to each frame Layer 1 Physical Undefined

Wired PhoneWired Phone

CO CO

AnalogVoice

Digital Bit Stream(1's & 0's) @ 64 Kbps

Generally analog from phone to CO One twisted Pair

At Central Office Filtered (BW about 3.5 KHz) Analog Voltage is Sampled 8,000 times/second Rounded off to 1 of 256 possible voltages Converted to a fixed length 8 bit code word

AnalogVoice

Ex) InternetEx) Internet

Local connection dedicates 64 Kbps to our use. ISP provides connectivity on a random, as needed, basis.

Location a

Location b

ISP Network

PC

PC

Internet Service Provider BackboneInternet Service Provider Backbone

1

3Router

TrunksAccess Line

Routers move packets from input to output.Packets get full trunk line speed.Trunk capacity shared randomly, as needed.

PC

PC 64 Kbps

45 Mbps

Internet Call SequencingInternet Call Sequencing Assuming an "Always On" 64 Kbps connection...

Similar to DSL or Cable Modem (but slower) ... Logical connections opened between end devices

TCP (Layer 5). Routers do not monitor!! Router I/O decisions based on Layer 3 IP address

Best match found in Look-Up Table Router Tables updated independently of traffic

‘Hello’ packets exchanged every 10 seconds with adjacent routers

More detailed routing information (who is connected to whom) exchanged intermittently

Router determines best output port, generally for blocks of hierarchical IP addresses

Moving Traffic with PacketsMoving Traffic with Packets Layer 7 Application Word Perfect


Maximum TCP Segment Size assumed to be 1460B(Parameter in Windows Registry)

Chops file into 2 x 1460B packets, adds 20B TCP Header to each Layer 3 Network IP

Adds 20B IP Header to each packet Layer 2 Data Link Undefined

Adds 10B Layer 2 Header to each frame Layer 1 Physical Undefined

Ex) ATMEx) ATM

Local Carriers dedicate 64 Kbps to our use. IXC provides random connectivity on an as-needed basis.

Location a

locationc

Carrier ATM Network

VC, a to/from c

PC

PC

ATM BackboneATM Backbone

ATM Switch

TrunksAccess Line

Switches move cells from input to output.Cells get full trunk line speed.Trunk capacity shared randomly, as needed.

ATM Call SequencingATM Call Sequencing End device requests logical connection Routing Protocol determines path thru network Affected Core Switches notified

Look-Up table updated to show proper output port where specific input cells should be placed

Switch resources (bandwidth, buffer space) reserved as appropriate

User appears to see dedicated nailed up bandwidth Path is known as a Virtual Circuit

TCP opens logical connection with far site Packets transferred, TCP logical connection closed

Switch resources released when user finished

Moving Traffic with ATM CellsMoving Traffic with ATM Cells Layer 7 Application Word Perfect


Maximum Segment Size assumed to be large, say 64 KB 2,920B file not segmented. Adds 20B TCP Header

Layer 3 Network IP Adds 20B IP Header

Layer 2 Data Link ATM Adds 8B padding & 8B SAR Trailer. Chops into 2976/48 = 62 cells (53 byte cell size). Adds 5B ATM

header to each cell. Layer 1 Physical Undefined

Internet Packet FormatInternet Packet Format

Traffic

?? 20 20 0-1460 ??

IP TCPLayer 2 Header

Layer 2 Trailer?

Probably originated or passed through an Ethernet.

Internet Protocal v4Internet Protocal v4

TOS

TTL

Source Address

Destination Address

4 Bytes

802.3LAN

LAN

OSU Campus Network (> 2001)OSU Campus Network (> 2001)

Routers

1 GbpsEthernet

OneNetEthernetSwitch

802.3LAN

802.3LAN

LAN

LAN

OSU 2009 Internet ConnectivityOSU 2009 Internet Connectivity

Example TracertExample Tracert

Handy site for figuring out who owns IP addresses:www.arin.net(has links to databases covering other regions)

Traceroute to WWW.CISCO.COMTraceroute to WWW.CISCO.COM

4 Internal OSU-Stillwater routers 3 OneNet routers (all in Tulsa?) 5 Cogent Communications routers

te4-3.ccr01.tul01.atlas.cogentco.com te2-2.mpd01.dfw01.atlas.cogentco.com

1 Akamai Technologies (Hosting Service) (3:30 pm, 12Sept11, rtt = 8 msec, 12 routers)

Traceroute to WWW.TULSA.COMTraceroute to WWW.TULSA.COM 4 Internal OSU-Stillwater routers 3 OneNet routers (Tulsa?) 4 Cogent Communications routers

te4-4.1052.ccr01.tul01.atlas.cogentco.com te0-2-0-7.ccr22.dfw01.atlas.cogentco.com

1 Global Crossing router GigabitEthernet2-3.ar2.HOU1.gblx.net

4 Routers in Houston te2-5.dsr01.hstntx2.networklayer.com

The Planet server (hosting service) (3:55 pm, 12Sept11, rtt = 14 msec, 16 routers)

# Routers not necessarily f(distance)# Routers not necessarily f(distance)

Launched 14 September 2011, 2 miles from OSU campus 1 Scheets' home router 5 SBC (now AT&T) & AT&T routers

dist2-vlan50.okcyok.sbcglobal.net ggr6.dlstx.ip.att.net

3 Cogent Communications routers te3-2.ccr01.tul01.atlas.cogentco.com

3 ONENET routers Probably in Tulsa, maybe Oklahoma City

3 Oklahoma State routers (11:19 am, 14Sept11, rtt = 71 msec, 15 routers)

Fall 2007 Weird Route Seen by StudentTulsa to OSU Stillwater

Fall 2007 Weird Route Seen by StudentTulsa to OSU Stillwater

Tracert launched from Tulsa, hitAtlantaWashington, D.C.IllinoisKansas CityTulsaOklahoma CityOSU Stillwater

Internet Protocal v6Internet Protocal v64 Bytes

Flow Label

Destination Address

Source Address

Hop Limit

RedNeckNet ISPRedNeckNet ISP

Salina

Joplin

Stillwater

Lubbock

Dallas

Little Rock

RedNeckNet VoIPRedNeckNet VoIP

Full MeshN(N-1)/2 Connections


Bus5 Connections


Star5 Connections

GradingGrading Real World:

1 team gets full credit Everyone else gets a zero

Partial credit Awarded on Quizzes & Tests NOT AWARDED ON DESIGN PROJECTS!

Real world designs don't get partial credit Either Work or They Don't

Double check your work!!! Use a spreadsheet

StatMuxStatMuxfrequency

tim

e

1

3

1

2

Different channels use all of the frequency some of the time,at random, as needed.

CDMCDMfrequency

tim

eDifferent channels use all of the bandwidth all of the time.

Channels use different codes. Other channels cause noise-like interference.

CDMA: 3D ViewCDMA: 3D View

code #1

code #2

code #3

frequency

time

N Read 2.3, 2.5 n Problems 1.6, 2.6, 2.8 n Quiz #1, Lecture 12, 4 February u Open book & notes u Calculators are allowed u No Smart Phones ECEN4533 Data.

Documents

network n

u lecture

n problems

n quiz

u switches

live u

packets n layer

points u